The present invention generally relates to a data recording carrier, and more specifically, is directed to a non-contact information medium containing an IC chip. A non-contact information medium containing an IC chip “implies such a medium that an IC chip is provided as an information recording medium, and this information recording medium communicates with an external device in a non-contact manner. As a result, if such an information medium is a non-contact type medium, then there is no limitation in wavelengths of electromagnetic waves, but also no limitation in communication distances. As a consequence, a non-contact IC module (will be discussed later), and a solid member containing such a non-contact IC module are equal to a “non-contact information medium”.
Also, the present invention generally relates to a communication system, and more particularly, is directed to a data communication system utilizing a non-contact information medium. A “non-contact information medium” is such a medium equipped with an information recording module such as an IC chip and communicated with an external device such as a reader/writer in a non-contact manner. As a result, if such an information medium is a non-contact type medium, then there is no limitation in wavelengths of electromagnetic waves, but also no limitation in communication distances.
A typical non-contact information containing an IC chip is known as such a non-contact IC card capable of communicating with a reader/writer by using microwaves. It should be understood in the present specification that an expression “IC card” may totally involve a smart card, an intelligent card, a chip-in card, a microcircuit (microcomputer) card, a memory card, a super card, a multi-function card, a combination card, and the like.
Also, a shape of such a non-contact information medium containing an IC chip is not limited to a shape of a card. As a result, this non-contact information medium may involve a so-called “IC tag”. In this case, a so-termed “IC tag” owns a similar function to that of an IC card. This IC tag may involve all of information recording media having various sizes equal to sizes of stamps and also smaller than the stamp sizes, namely ultra-small sizes, and further having various shapes such as coins.
On the other hand, an IC card is classified into either a contact type IC card or a non-contact type IC card in accordance with a communication method executed between an IC chip build in an IC card and a reader/writer. Among them, a non-contact IC card may have the following features. That is, since this non-contact type IC card owns no contact used with the reader/writer, no loose contact will occur. This non-contact IC card may be used at a remote placer from the reader/writer by several cm to several tens cm. The non-contact IC card may be protected from soil, rain, and electrostatic energy. Accordingly, higher needs of such a non-contact IC card will be expected.
A non-contact IC card may obtain operating electric power from an electromagnetic wave received from a reader/writer by way of an electromagnetic induction, and also may exchange data with respect to the reader/writer by utilizing electromagnetic wave. Normally, in a non-contact IC card, while an antenna (for example, antenna coil) used to transmit/receive such an electromagnetic wave is formed as a separate member from an IC chip, this formed antenna is connected to the IC chip.
As explained above, since the antenna and the IC chip are formed in the independent members, when the conventional non-contact IC card is packaged, or mounted, both the antenna and the IC chip are required to be electrically connected to each other. However, the electric connection between the terminals of such a very small IC chip and the antenna would cause technical difficulties. Further, when a flexible IC card is used, stress is especially applied to a connecting point, which may cause disconnection of the electric connection. Also, since a board for holding the IC chip and the antenna is required, this board may cause manufacturing cost to be increased. In addition, since checking of the electric connection and also confirming of the operation of the IC chip cannot be carried out unless both the IC chip and the antenna are mounted and connected to each other, the manufacturing sufficiency would be lowered.
On the other hand, to accept such a request for making constructive elements compact and for establishing multi-functions, an on-chip coil system may be conceived in which an antenna coil is build in an IC chip. This IC chip may have such a merit that there is a less problem in packaging, and this on-chip coil system may contribute compactness of these constructive elements.
However, since the antenna of the non-contact information medium is made compact, the communicatable region thereof is necessarily decreased, and there is a limitation in the applicable range, as compared with that of the conventional IC card equipped with the card-sized antenna, which is externally provided with the IC card.
Also, to supply electric power from a reader/writer to a card and also to transfer data from the reader/writer to the card, such a high frequency (radio frequency) carrier signal of a frequency “fc” (for example, fc=several hundreds kHz to several tens MHz) is employed. On the other hand, to transfer data from a card to a reader/writer, the above-explained carrier frequency may be directly utilized. Alternatively, a sub-carrier frequency “fsc” is modulated by the sub-carrier frequency “fsc” (for instance, fsc={fraction (1/16)} to 32 fc) which is sufficiently lower than “fc” in order to improve S/N (signal to noise) and reliability of communications.
Also, to establish the wireless communication between the conventional non-contact IC card and the reader/writer, the antenna (for example, antenna coil) of this non-contact IC card is required to be arranged in such a condition that the antenna (for instance, antenna coil) of this non-contact IC card is positioned in parallel to and also just above the antenna (for example, antenna coil) of the reader/writer. For instance, even when the non-contact IC card is located just above the reader/writer, if the antenna coil of the non-contact IC card is inclined with respect to the normal direction of the antenna coil of the reader/writer, then the communication distance would be shortened in accordance with the inclination angle due to the antenna directivity. When the normal direction of the antenna coil of the non-contact IC card is positioned perpendicular to that of the antenna coil of the reader/writer, no longer the communication can be established between the non-contact IC card and the reader/writer.
Furthermore, in such a case that the non-contact IC card is separated from the position just above the antenna of the reader/writer, the non-contact IC card can communicate with the reader/writer, because of the antenna directivity. After all, the communicatable region is limited only to such a predetermined area located just above the antenna of the reader/writer.
As previously explained, while the conventional non-contact IC card communicates with the reader/writer, there are various restrictions, namely restriction in antenna inclination angle caused by antenna directivity, restriction in communicatable area, and restriction in communication distance. Also, since the users of the non-contact IC cards cannot visually observe the communicatable areas, operatabilities of these card users are deteriorated and these card users cannot quickly read out.